Resin Mold Shrink-Rate Chart ALL RESINS HAVE DIFFERENT SHRINK RATES DEPENDING ON THE PLASTIC FAMILY. AMORPHOUS VS. CRYSTALLINE PLASTICS, TOOLING DESIGN, PROCESS CONDITIONS (CYCLE TEMPERATURE AND TIME) ALONG WITH THE DESIGN OF PART (WALL THICKNESS AND WALL CONSISTENCY). PLASTICS ALSO SHRINK DIFFERENTLY WITH THE DIRECTION OF FLOW. THE CHART REFLECTS TYPICAL SHRINKAGE RATES FOR THE MOST COMMONLY USED PLASTICS. RESIN TYPE SHRINK INCH/INCH POLYPROPYLENE-UNFILLED .015”/.018” POLYETHYLENE .020”/.025” ABS .0035” HIPS .0035” GPPS .0035” POLYCARBONATE .007” PC-ABS .007” ACRYLIC .003”/.004” NYLON 6/6 -UNFILLED .020” NYLON 6/6 (33% SHORT GLASS) .0035” PBT .015” ACETAL (POM) .020” ACETAL HOMOPOLYMER .018”/.020” PVC RIGID .0035” TPE SANTOPRENE .014”/.018” NORYL .005”/.007” NORYL (30% GLASS FILLED) .001” TPU .007”/.010” POLYSULFONE .007”
TPU - Thermoplastic Polyurethane Elastomer Thermoplastic polyurethane elastomers exhibit excellent abrasion and wear resistance and high tensile and tear strengths. TPUs are tough, durable, easy to clean and well-suited to applications that demand the elasticity of rubber combined with high stability. In addition, the inherent translucency of these products makes it easy to color and that is an added benefit in many applications. Applications: Automotive and Aerospace Applications, Medical and Optical purposes, Electrical Wire and Cable Coverings. Tensile Strength Flexural Modulus Impact Strength Max Temp. Chem. Resistance 6960-12,000 psi 260,000-340,000 psi .80-10.1 ft-lb/in notched izod 160°-250° F Fair to Good Advantages Chemical Resistant Low temp. flexibility Abrasion and wear resistant Easily Processed Disadvantages Shorter shelf life Lower Stiffness than similar PET Drying required pre-processing Narrow hardness range Brand Names: Celanex, Valox, Ultradur.
TPR - Thermo Plastic RubberThermoplastic elastomers (TPE) are a combination of polymers (usually a plastic and a rubber) which consist of both thermoplastic and elastomeric properties resulting in a product that is extremely easy to use in manufacturing a variety of products. TPEs require little or no compounding and no need to add reinforcing agents, stabilizers or cure systems. Applications: Automotive Fluid Delivery Systems, Household appliances, Sporting goods, Electrical and Medical components. Tensile Strength Flexural Modulus Impact Strength Max Temp. Chem. Resistance 1,000-7,000 psi 5,000-800,000 psi 2.5-No Break ft-lb/in notched izod 200°-300° F Fair to Good Advantages Low compression and tension set Easily processed Fatigue resistance Good tear strength Disadvantages Flammable but flame retardant grades available Extensive heat aging causes severe change in mechanical properties High cost Brand Names: CoolPoly, Dynaflex, Elastamax, Monprene, Versaflex.
SAN - Styrene AcrylonitrileSAN is ABS without the Butadiene. It does not have the Impact Strength of ABS, but can be crystal clear. Styrene Acrylonitrile has better general chemical resistance than polystyrene and is cheaper than acrylic. It has a good combination of rigidity, strength, toughness and transparency. Applications: Battery cases, Dials, Knobs, Switches, Lenses, Trays, Containers, Covers, Autoclavable devices, Dental & Medical light diffusers Tensile Strength Flexural Modulus Impact Strength Max Temp. Chemical Resistance 10,000-18,000 psi 500,000-1,200,000 psi .3-3.0 ft-lb/in notched izod 140°-200° F Poor to Fair Advantages Heat Resistant High Clarity High Flow and Rigidity Dimensionally Stable Disadvantages Low impact strength High processing temps Flammable-smoke generation Yellows quicker than other PS Brand Names: LNP Lubricomp, Thermocomp, LG, Lustran, Luran.
PVC - PolyvinylchloridePVC is one of the oldest and most commonly used thermoplastic materials. The material is a colorless polymer of vinyl chloride. PVC can have numerous properties and the characteristics can be altered by the use of additives such as stabilizers, lubricants, softeners, pigments, fillers or static agents. PVC offers similar properties to ABS at a slightly reduced cost. However, the appearance of PVC cannot come close to ABS. In its plastic phase, PVC is corrosive to molds and molding machines. In its solid phase, PVC is non corrosive.Applications: Medical/Healthcare Products, Automotive Applications, Household Items and Electronic Extruded Wire Covering.Tensile StrengthFlexural ModulusImpact StrengthMax Temp.Chemical Resistance10,000-12,000 psi350,000-600,000 psi8-1.4 ft-lb/in notched izod120°-170° FFair to Good AdvantagesWide range of flexibilityFlame RetardantDimensional stabilityLow CostDisadvantagesAttacked by several solvent typesLimited thermal capabilityOver heating may cause harmful vaporsStained by sulfur compoundsHigher density than many plasticsBrand Names: Alpha, Apex, Evicom, Geon, LG.
PSU - Polysulfone Polysulfone is a high temperature amorphous material with relatively low cost. It is transparent and can be used at temperatures of up to 300 F. Polysulfone has been compounded, with glass and mineral filled grades available. Applications: Appliance parts, electronic parts, automotive parts, medical components, business Equipment, aerospace and insulators. Tensile Strength Flexural Modulus Impact Strength Max Temp. Chemical Resistance 9,500-18,000 psi 390,000-1,500,000 psi .65-7 ft-lb/in notched izod 300°-350° F Fair to Good Advantages Good thermal stability Transparent Tough and rigid Chemical Resistance Disadvantages Attacked by many solvents Poor weatherability Subject to stress cracks High processing temperature Brand Names: Udel, Ultrason, Mindel.
HDPE -High Impact Polyethylene High Impact Polystyrene is what its name implies. A few cents more than crystal styrene, to pay for the rubber modifier. HIPS is opaque and very widely used. It has a lower modulus, better elongation, and is a lot less brittle than crystal styrene. Applications: Household Goods, Containers, Furniture, Housings and Packaging. Tensile Strength Flexural Modulus Impact Strength Max Temp. Chemical Resistance 7,500-10,000 psi 160,000 -370,000 psi 3-7 ft-lb/in notched izod 100°-150° F Poor Advantages Optical clarity High gloss FDA grades available Low cost Good dimensional stability Good rigidity Disadvantages Flammable, but flame retardant grades available Poor solvent resistance Homopolymers are brittle Subject to stress and environmental cracking Brand Names: Certene, Hival, Polystyrol, Styron
PS - Polystyrene Crystal Crystal polystyrene is the cheapest thermoplastic available. It has properties to match its price. It is transparent and has good optical properties. It has very low Impact Strength. Applications: Household Goods, Containers, Furniture, Housings and Packaging. Tensile Strength Flexural Modulus Impact Strength Max Temp. Chemical Resistance 5000-7500 psi 380,000 -480,000 psi .35-.45 ft-lb/in notched izod 100°-150° F Poor Advantages Optical Clarity High gloss FDA grades available Low cost Good dimensional stability Good rigidity Disadvantages Flammable, but flame retardant grades available Poor solvent resistance Homopolymers are brittle Subject to stress and environmental cracking Brand Names: Certene, Hival, Polystyrol, Styron.
PPS - Polyphenylene Sulfide PPS is a high temperature semi-crystalline material. It has good mechanical properties and excellent chemical resistance at elevated temperatures. PPS has been compounded extensively and many different types of properties are available. PTFE filled PPS is one of the best bearing materials available. Unfilled grades of PPS have poor properties, so components are usually made from glass filled or glass/mineral filled grades. PPS is very sensitive to molding conditions and must be processed properly to achieve its maximum potential. Applications: Hydraulic components, bearings, cams, valves and electronic parts Tensile Strength Flexural Modulus Impact Strength Max Temp. Chemical Resistance 14,000-28,000 psi 550,000 -2,900,000 psi .5-6 ft-lb/in notched izod 450°-500° F Good to Excellent Advantages Capable of extended usage at 450° F Good radiation resistance Good solvent and chemical resistance Excellent dimensional stability Flame retardant Low water absorption Disadvantages Difficult to process (high melt temps) High cost Fillers [...]
PPA - Polyphthalamide PPA is a relatively new, semi-crystalline material, with an excellent cost to performance ratio. PPA bridges the performance gap between nylons/polyesters, and higher priced, high temperature materials such as PEI and PEEK. PPA has excellent impact strength and is not notch sensitive. PPA does absorb moisture, and its properties change as a result. This change is not nearly as great as 6-6 nylon. Despite its relatively recent introduction, good design data is available for PPA. Applications: Automotive applications, Housing for high temperature electrical connectors, Multiple other uses as a replacement to metals. Tensile Strength Flexural Modulus Impact Strength Max Temp. Chemical Resistance 9,000-33,000 psi 270,000 -2,700,000 psi .6-22 ft-lb/in notched izod 300°-450° F Good to Excellent Advantages Heat resistance Chemical resistance Can resist infrared soldering environments Relatively low moisture absorption Strength or physical properties Disadvantages Not inherently flame retardant Requires good drying equipment High processing temperatures Brand [...]